Railway maintenance machine for track levelling and alignment with the capacity to operate without interruptions in its advance on straight tracks and to operate on track turnouts tamping the diverging track

ABSTRACT

Railway maintenance machine for track levelling and alignment, with the capacity to operate without interruptions to its advance on straight tracks, to operate on track turnouts, and with the capacity to tamp the diverging track, characterised in that it comprises a lifting and slewing unit with a duplicated power system at the front end and at the rear end of said unit, where the lifting and slewing unit comprises a lifting trolley ( 21 ), with two pairs of hydraulic cylinders ( 27 A and  27 B) arranged so as to exert force to lift the track, and a slewing trolley ( 20 ) with two pairs of hydraulic cylinders ( 28 A and  28 B), arranged so as to exert force to modify the lateral position of the track, where said power system at the front end exerts force to carry out approximately 80% of the levelling and alignment needed by the track and where said power system at the rear end exerts force to carry out the rest of the levelling and alignment needed by the track to reach its definitive position.

RELATED APPLICATION

This application claims the benefit of priority of Spanish Patent Application No. 201530363 filed Mar. 18, 2015, the contents of which are incorporated herein by reference in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The invention belongs to the technical sector of railway maintenance and construction. More specifically, with regard to levelling, alignment and tamping machines and specifically to those machines which have the capacity to operate in a continuous manner, that is to say without halting at the sleeper which is being worked upon. In addition, the invention has the capacity to work on turnouts, with different work elements with regard to those machines which can only work on straight tracks.

The passage of the different vehicles that circulate on railway tracks and their exposure to meteorological conditions modify the qualities of the track and the rest of the elements upon which they lie. In order to correct the loss of these qualities and to keep the tracks from becoming impossible to use, it is necessary to carry out a series of maintenance jobs. With the current state of the art, the process of track alignment and levelling is undertaken by machines equipped with levelling units, also known as lifting units, and alignment units, also known as slewing units, ballasting the sleepers with tamping units.

In the state of the art there are models of machines or groups of machines, as well as patents related to this sector. A series of general characteristics can be established for all of these machines, formed of a track-tamping machine with a frame of tools with tamping units, characterised by the transmission of a vibratory force to the ballast upon which the sleepers rest. The machines also have lifting and alignment units at their front depending on the direction of work. These units are complemented with various measuring mechanisms which allow the transversal and vertical movement of the track to be controlled.

Focusing specifically on machines with the capacity to work on turnouts, there are also various patents which characterise the working equipment for adapting to these circumstances.

For example, in the case of lifting and alignment units, patent application ES-0480490 reveals a device for lifting and/or aligning the track laterally, especially in areas with points, crossings or similar, which is equipped in each case with a lifting tool, especially a lifting hook, which are developed to be adjustable through the use of actuators which are actuated by force so that they attack under the rail head or foot.

In the case of tamping units, there are also various solutions in the state of the art including patents and/or patent applications for operating on turnouts, tamping under the sleeper in the area of the diverging track. For example, in the patent EP-0455179-B1 it is shown how four tamping units are mounted with the capacity for transversal movement with regard to the main frame. What is more, the outer units have the capacity to rotate on a longitudinal axle. In this way an increase is seen in the transversal distance at which the machine is able to tamp the track with regard to the central axle.

Additionally, with regard to the main characteristics of these machines, there is a group of machines which are characterised by their ability to work in continuous movement. This means that the main frame does not stop for each tamping cycle of the machine. In order to do this, these machines have some type of mechanic or hydraulic system, generally electronically controlled, which allows for a relative longitudinal movement between the main frame and the work groups which must remain fixed with regard to the track whilst operating. The most typical solution within the state of the art is machines that have a second frame upon which the aforementioned work groups are mounted. This frame, generally referred to as a satellite frame, is supported over the track through the use of rolling railway elements (axles or bogies).

In the patent ES-2397739-B1 a system is described for controlling the longitudinal movement of these work groups with regard to the machine's main frame without the need to use a second frame supported over the track with rail wheels. According to this patent, this is achieved by a series of hydraulic devices which control the longitudinal movement and by giving the cylinders which act upon the additional lifting trolley the capacity to pivot in all directions.

In general, the currently existing tamping units are characterised by delivering a closing force to the tines which penetrate the ballast banks and ballast the sleepers by causing the stones to flow under the sleepers. This force has a fixed component, exercised by a hydraulic cylinder, and an oscillating component. The most typical solution for generating this vibrating force is the use of an axle with eccentric geometry, which is made to turn at particular rates of revolution in order to achieve the desired frequency. Other solutions also exist, such as that presented in patent ES-2027048-B1, in which this oscillating force is achieved through the action of a system formed in essence by a hydraulic actuator powered by power-discharge distribution valves which are controlled in cyclical sequence by one or more distributing means.

Another characteristic of the tamping units is the manner in which the opening of the tines is adapted to differentiate the operations carried out in areas where the rail rests on double sleepers, instead of single sleepers which is the most common. To do so, the machines usually limit the course of the hydraulic cylinder which carries out the opening and closing of the tines. This limitation usually takes the form of a metallic body articulated over the sleeve of the cylinder for opening and closing tines. This body limits the course of the piston rod in operations on single sleepers. When it is necessary to tamp double sleepers, a secondary cylinder removes the articulated body, allowing the piston rod to run its maximum course. In the patent U.S. Pat. No. 6,401,623-B2 a system is disclosed which eliminates this mechanical-hydraulic system by hydraulically limiting the volume of oil which enters the cylinder's chamber in the case of tamping single sleepers.

SUMMARY OF THE INVENTION

It is necessary to offer an alternative which covers the deficiencies to be found in the current state of the art.

With this aim, the invention at hand provides a railway maintenance machine for track levelling and alignment with the capacity to operate without interruptions in its advance on straight tracks, to operate on track turnouts and with the capacity to tamp diverging tracks.

Unlike existing railway maintenance machines, the machine of the invention is comprises, and is characterised by, a lifting and slewing unit with a power system at its front end and another power system at the rear end of said unit, where the lifting and slewing unit comprises a lifting trolley (21) with two pairs of hydraulic cylinders (27A and 27B) arranged so that they exert a vertical force to lift the track and a slewing trolley (20) with two pairs of hydraulic cylinders (28A and 28B) arranged so that they exert a horizontal force to modify the lateral position of the track, where the aforementioned power system at the front end exerts force to carry out 80% of the levelling and alignment needed by the track and where said power system at the rear end exerts force to carry out the rest of the levelling and alignment needed by the track in order to reach its definitive position, and where said lifting trolley (21) and said slewing trolley (20) transmit the vertical and horizontal forces to the track independently and where the slewing trolley (20) is supported on and rolls along the track and has four hydraulic cylinders (23) which elevate the lifting trolley (21) thus eliminating the existing play between said lifting trolley (21) and the rail, pre-positioning the lifting trolley (21) fixed to the track to obtain a better transmission of the force of the power system of said lifting trolley (21).

Embodiments of the invention are described according to the attached claims in a subsequent section.

The machine, in accordance with the aspects of the invention described above, presents a series of advantages with regard to the prior art. These can be summarised as follows:

-   The invention at hand allows for the simplification of the current     structure of continuous on-track tamping machines, reducing its cost     due to lower manufacturing and maintenance costs in comparison with     those currently on the market. -   The tamping vibration is transmitted by a hydraulic cylinder     controlled by a high-frequency servo valve, which allows for an     adjustment in intensity and frequency without the need for any     additional mechanical or hydraulic element. This characteristic     combines the advantages both of being able to dispense with an     eccentric rotating axle and the capacity to be set for double     sleepers, all of this without needing to incorporate any additional     mechanical, hydraulic or electronic component.

These and other advantages shall become clear in light of the detailed description of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The aforementioned advantages and other advantages and characteristics shall be more fully understood from the following detailed description of embodiments, with reference to the attached drawings which should be considered illustrative in nature and not as limiting, in which:

FIG. 1 shows the side view where the work elements object of the invention are positioned in the direction of work.

FIG. 2 shows the perspective view of the lifting and slewing unit, where its main constructive elements are indicated.

FIG. 3 shows the side view of the lifting and slewing unit, where the position of the power system's cylinders in a backward position can be seen.

FIG. 4 shows the side view of the lifting and slewing unit, where the position of the power system's cylinders in forward position can be seen.

FIG. 5 shows the perspective view of the tamping unit and moving trolley, where its main constructive elements are indicated.

FIG. 6 shows the overhead view of the tamping unit and moving trolley, where its longitudinal course can be seen.

FIG. 7 shows the detailed perspective view of each of the two moving trolleys with their two corresponding tamping units.

FIG. 8 shows the side view of the tamping unit and moving trolley where the capacity to tamp the diverging track through transverse movement and the rotation of the tamping units can be seen.

FIG. 9 shows the side view of a tamping unit, where its main components and those of the vibration cylinder are indicated. With two different figures, the movement of closing and adaptation for double or single sleepers is represented.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The elements defined in this detailed description are given to aid in an overall understanding of the invention. Consequently, those skilled in the art will recognise that variations and modifications of the embodiments described in this document can be carried out without straying from the scope and spirit of the invention. What is more, the detailed description of those functions and elements which are already sufficiently known are omitted with the aim of being clear and concise.

The invention relates to a machine capable of moving along a railway track with a series of work units. According to the direction of movement, the first work unit is that called the lifting and slewing unit, which is capable of manipulating the track in order to bring it into the desired position. Following this, the machine has four tamping units with the capacity to ballast the track into the new position. The electronic systems and equipment needed to carry out the track measurement and to control the aforementioned work units are similar to those used in the current state of the art, and so are beyond the scope of this description.

In order to allow the main frame of the machine to work in a continuous manner without interruptions to its advance, the lifting and slewing units and the tamping units move longitudinally with regard to the machine's main frame through the use of cylinders.

The invention comprises the lifting and slewing unit, such that it is made up of two independent bodies joined together by connecting rods that enable a vertical movement of some 100 mm.

The first body transmits the slewing force to the track. It rests on the track as it works thanks to two axles with their corresponding wheels. Supported on this trolley, through the use of two rods and four cylinders, is the lifting device, which uses four pairs of rollers that are able to fix themselves vertically to the railhead. It also has two hooks able to hold on to the rail under the rail's foot in order to be able to work on turnouts. Each of the hooks moves along each side of the machine actuated by hydraulic actuators.

The lifting and slewing force is carried out through the use of a power system formed by various hydraulic cylinders. These cylinders have fixed fasteners that pivot on the frame so that they can adapt to any trolley position. Thus the power system which enables the work on the track is doubled. Each system is composed of a pair of lifting cylinders parallel to each other and two slewing cylinders which attack at an angle with regard to the unit. In order to avoid the vertical component of these cylinders interfering with the lifting cylinders, double pistons are used so that when one wishes to move the track to one side, the force of the cylinder pushing the trolley is equal to that of the one pulling the trolley. Due to the geometric configuration, the transversal components of the force executed by each cylinder are added together, while the vertical components cancel each other out.

As attack points of the cylinders are fixed to the frame, their working angle varies according to the position of the trolley, which is mobile. In the central, furthest back position of the unit, the four lifting cylinders are parallel to each other and completely vertical in order to have more net force in this position. However, the slewing cylinders are situated in such a way that the front pair are on a perpendicular plane with regard to the track when the trolley is in its furthest forward position, while when the trolley is in its furthest backward position, it is the rear pair of cylinders which assume this position. In this way, the loss of perpendicularity, and thus of transversal force, from one pair of cylinders is compensated by the gain in the other pair, resulting in a net transversal force which is practically constant. This aspect is also considered a difference with regard to the current state of the art.

The first power system, which is situated at the front of the unit, carries out 80% of the modification required to bring the track into its final position. The second system, which is situated at the rear of the unit, brings the track into its definitive position.

In turn, the tamping units move longitudinally to the machine's frame, guided by columns that are parallel to the track axis. The machine's electronic system operates the cylinder's control servo valve, which controls this movement so that the tamping unit remains fixed with regard to the sleeper(s) being tamped. The aforementioned transversal columns, which enable the longitudinal movement, are mounted on a subframe, which is supported on two rows of rollers which are fixed to the frame of the machine. These rollers are arranged in such a way that they allow the subframe to move between 700 and 900 mm towards the exterior of the machine. What is more, each tamping unit has the capacity to rotate on its corresponding guiding column. The sum of this rotation and the transversal movement allow the diverging track to be tamped at some 2,500-3,000 mm from the central axis of the track.

In these tamping units, the closing force transmitted to each tine-holder is carried out by a single hydraulic cylinder. The cylinder is composed of three coplanar chambers. The central chamber commands the vibratory force through a high-frequency servo valve, which is powered by a PLC with a square wave signal. This wave is adjustable in amplitude and frequency in order to adapt the work of the machine to the characteristics of the ballast. Thus in the central chamber an oscillating movement is achieved of an amplitude which is variable between 2 and 6 mm, at frequencies of between 20 and 38 Hz, according to the total power one wishes to transmit to the ballast. The length of the cylinder's sleeve has been calculated so that when it is in its lifted position the tine is positioned for work on double sleepers. In a similar manner, in its extended position the tine is positioned for work on a single sleeper. It is around this selected position that the piston rod carries out the oscillating movement. This characteristic is considered a difference with regard to the current state of the art, combining the advantages of doing without an eccentric rotating axle and having the capacity to be positioned for work on double sleepers, all of this without the need to incorporate any additional mechanical, hydraulic or electronic component. This means large savings with regard to both the initial cost and subsequent maintenance of the unit, as the only wearing parts are commercially-available joints and lip seals. What is more, the cylinder system described here allows the vibration to be stopped in those phases of work where it is not necessary, unlike eccentric systems, where the mechanical inertia of the elements makes this operational intermittency impossible. In this way, vibration is only transmitted to the tine-holder during the penetration in the stones and the closing of the tines, which makes up about a third of a continuous work cycle.

The two side chambers of the cylinder, which face the opposite direction from the central chamber, transmit the constant closing force to the tine. These two chambers are powered by the same valve in order to guarantee the symmetry of the forces applied to the assembly.

In summary, and as a preferred exemplary embodiment, a machine has been conceived which is capable of moving along a railway track with a series of work units. According to the direction of work, the first work unit is that called the lifting and slewing unit, capable of manipulating the track position in order to bring it into the desired position. The power system used to achieve this is duplicated, both for alignment and levelling. The first system positions the track at 80% of its final position and the second system brings the track into its definitive position. Both systems compensate between themselves the power variations they each have, the first system loses perpendicularity while the second gains perpendicularity due to the movement of the frame with regard to the lifting and slewing trolley. The tamping units, in independent elements, are responsible for ballasting the track.

The lifting and slewing trolley, as is shown in FIG. 2, is composed of a slewing trolley (20) with two axles with wheels that rest on the track. The lifting trolley (21) rests on this trolley by means of two rods (22) and four cylinders (23) and uses pairs of rollers, or hooks (25) in the case of turnouts, with the capacity to fix themselves vertically to the railhead (24) through the use of hydraulic actuations and to pull on it.

In a first phase at the beginning of the lifting process, these rollers or hooks close and, through the use of the cylinders supported on the slewing trolley (23) they tauten in a vertical direction over the railhead. The force required to lift the track is applied to the lifting trolley through the use of two pairs of cylinders arranged vertically (27A and 27B), with the capacity to pivot on a fixed point of the machine's frame. Upon lifting the track, it drags along with it the slewing trolley (20) over the other two pairs of cylinders (28A and 28B), also pivoting on the machine frame, which modify the lateral position of the track.

In order for the machine to work in a continuous manner and without stopping, as the lifting and slewing trolley is anchored to the track it is necessary to have a relative longitudinal movement between the lifting and slewing unit and the frame of the machine. In order to achieve this, the unit is connected to the frame of the machine by the use of cylinders (29) which enable the aforesaid movement.

The two pairs of lifting cylinders (27A and 27B) are arranged so that their axles remain parallel throughout the work process. This process begins with the cylinders inclined at an angle of 10° to the longitudinal vertical plane of the machine, as can be observed in FIG. 4, and it ends when they are at an angle of 0°, as shown in FIG. 3.

The servo valves that actuate upon the cylinders supply the amount of oil necessary to recover the loss of the cylinders' course depending upon the angle of inclination at which it is positioned and the value of lifting desired, always consisting of positive upwards work.

The two pairs of slewing cylinders (28A and 28B) are arranged so that at the beginning of the process, in the furthest forward position of the slewing trolley with regard to the frame of the machine, as can be seen in FIG. 4, the two cylinders which are over the front axle are vertical on the vertical longitudinal plane of the machine and those of the rear axle are at an angle of 10°. As the machine advances, the slewing trolley being fixed to the track, the front-axle cylinders lose verticality and the rear axle cylinders gain it until they reach verticality, as can be seen in FIG. 3.

In this manner, apart from compensating the loss in power, the servo valves which command the cylinders only need to supply the oil to correct the errors in the track, as the differences in the magnitude of the cylinders according to where the slewing trolley is situated with regard to the frame are compensated. That is to say, the front-axle cylinders gain magnitude and the rear-axle cylinders lose it in the same proportion.

The tamping units are responsible for ballasting the track positioned by the lifting and slewing units, introducing ballast beneath the sleepers. The layout of a tamping unit can be seen in FIGS. 5 to 9.

In total, the machine has four units (12), arranged in pairs on a common trolley (2), each one operating on one rail of the track, as can be seen in FIG. 7. Each trolley has two longitudinal columns, parallel to each other (9) and fixed by elastic couplings (8). A central body, referred to as the shuttle (13), is assembled, which has two through-holes arranged so that it can move longitudinally along the columns (9), remaining fixed in the other directions. This shuttle (13) has in turn another two pairs of axles, coaxial in pairs. Through the use of axles (14), each respective unit is assembled (12) and they operate separately on the inner and outer portions of the track. In this configuration, the shuttle (13) and the two tamping units (12) move together, only allowing rotation with regard to the fixing axle (14).

These elements have been designed so that the total course of the longitudinal movement of the shuttle (13) within the trolley (2) is 600 mm. In this way, through the adequate control of the longitudinal hydraulic cylinders (10), the machine can ballast the track without interrupting its advance, maintaining the tamping units in a fixed position with regard to the sleeper being operated on.

Each trolley also has the possibility of moving independently to either side in a transversal direction in order to be able to reach and tamp the diverging track in turnouts, as can be seen in FIG. 8. Each trolley (2) is supported at its front and rear ends by rows of 14 aligned rollers (1), which are fixed to the frame of the machine along its transversal direction. A pair of hydraulic cylinders (3) allows a movement of 850 mm, of which 150 mm are in an inwards direction in order to compensate the sag of the tighter curves.

The trolleys are guided at their side with anti-wear plates, the position of which can be adjusted (4). On the upper surface, a brake shoe (5) articulated to the frame by a set of rods (6) transmits a descending vertical force carried out by the corresponding brake cylinders (7). The force of friction eliminates the play in the system, prevents the trolleys from moving sideways when the unit is working, and also relieves the rollers (1) from part of the ascending vertical force generated by the tamping units (12) whilst working.

Lastly, with the aim of increasing the effective tamping distance, reaching all of the central portion of the track and up to 2900 mm outwards from the central axis, each tamping unit (12) has the capacity to rotate 20° with regard to the shuttle (13) on the axle (14) from which it hangs. This movement is controlled by the hydraulic cylinder (11).

Each tamping unit, as can be seen in FIG. 9, is composed principally of a main body, referred to as the chassis (15), which can rise and descend to the working position, guided by a pair of fixed columns (16), through the action of the chassis-lowering cylinder (17). A total of four vibration cylinders (18) are controlled by their corresponding high-frequency electro valve (32). The action of each of the cylinders opens and closes its associated tine-holder (19), with the capacity to rotate in its central part on the chassis. Each cylinder has a central rod (30). As this rod is opened or lifted (30) the opening of the tine-holder (19) adapts to work on single or double sleepers. The central rod (30) vibrates with regard to the selected position as is required in each phase of the work. In this way, this rod remains fixed in order to minimise the wear to wearing parts, and it only vibrates during the penetration of the tine into the stones and the closing of the tines. The vibration adapts to the characteristics which are optimal for each of these phases. In this way, when the tines reach the height of the ballast during the lowering of the chassis, the vibration begins at 25 Hz and an amplitude of 5.6 mm to favour the penetration into the stones. When the unit reaches closing position, the vibration adjusts to 35 Hz and 3.5 mm in order to help the ballast shift under the sleeper which is being worked upon.

Another pair of rods (31), fixed to the chassis (15) transmits a constant tine-closing force to the system during the closing of the tines. 

What is claimed is:
 1. A railway maintenance machine for track levelling and alignment, with the capacity to operate without interruptions to its advance on straight tracks, to operate on track turnouts, and with the capacity to tamp the diverging track, characterised in that it comprises a lifting and slewing unit with a power system at the front end and another power system at the rear end of said unit, where the lifting and slewing unit comprises a lifting trolley (21), with two pairs of hydraulic cylinders (27A and 27B) arranged so as to exert vertical force to lift the track, and a slewing trolley (20) with two pairs of hydraulic cylinders (28A and 28B), arranged so as to exert horizontal force to modify the lateral position of the track, where said power system at the front end exerts force to carry out approximately 80% of the levelling and alignment needed by the track and where said power system at the rear end exerts force to carry out the rest of the levelling and alignment needed by the track to reach its definitive position, and where said lifting trolley (21) and said slewing trolley (20) transmit the vertical and horizontal forces to the track independently, and where the slewing trolley (20) is supported on and rolls along the track and has four hydraulic cylinders (23) which elevate the lifting trolley (21), thus eliminating the existing play between said lifting trolley (21) and the rail, pre-positioning the lifting trolley (21) fixed to the track to obtain a better transmission of the force of the power system of said lifting trolley (21).
 2. The railway maintenance machine according to claim 1, characterised in that each of said pairs of hydraulic cylinders (27A and 27B) of the lifting trolley (21) are arranged parallel to each other and articulated to a fixed point of the frame of said machine, in such a way that in the position corresponding to the final moment of the work cycle, in the furthest backwards position of the lifting and slewing unit, said pairs of hydraulic cylinders (27A and 27B) are parallel to the vertical axis of the machine, in such a way that during the relative backwards movement of said lifting and slewing unit during the work cycle, said hydraulic cylinders (27A and 27B) act by shortening their length, either to adapt to said backwards movement or to carry out lifting on a point of the corresponding rail of the track being operated upon.
 3. The railway maintenance machine according to claim 1, characterised in that said two pairs of hydraulic cylinders (28A and 28B) of the slewing trolley (20) are articulated to a fixed point of the frame of said machine in such a way that in the position corresponding to the initial moment of the work cycle, with the lifting and slewing unit in its furthest forward position, the pair of hydraulic cylinders (28A) situated in the front position (28A) is contained within the plane perpendicular to the track, while at the end of the work cycle, it is the pair of hydraulic cylinders (28B) situated in the rear position that is contained in said plane, in such a way that the power loss of one system is compensated by the gain in the other due to the variation in perpendicularity with regard to the track during the movement of the lifting and slewing unit.
 4. The railway maintenance machine according to claim 1, characterised in that it comprises four tamping units (12) for continuous work, where said tamping units (12) are arranged in pairs on a rigid common trolley (2) and where each tamping unit (12) moves guided by two columns parallel to each other (9) through the action of a hydraulic cylinder controlled by an electronic system in such a way that the unit remains fixed with regard to the sleeper being operated upon during the tamping cycle.
 5. The railway maintenance machine according to claim 4, characterised in that each of the two tamping units (12) situated on said common trolley (2) is arranged to operate on each rail of the track, respectively, and with the capacity to move in a transversal direction with regard to the machine, where upon said parallel columns (9) a shuttle (13) is situated, arranged to move on said columns (9), and where from said shuttle (13) said two tamping units (12) hang, one interior and the other exterior with regard to the corresponding rail of the track, and with the capacity to rotate on a fixing axle (14).
 6. The railway maintenance machine according to claim 4, characterised in that the aforesaid trolley (2) comprises hydraulic brake cylinders (7) articulated to the frame of the machine by a set of rods (6), where said hydraulic brake cylinders (7) are capable of exercising a downwards vertical force through the use of a brake shoe (4) on the upper surface of said trolley (2), where said force allows the trolley (2) to brake in the desired transversal position, apart from also cancelling out the vertical play in the system supported on rollers (1) during the work of the tamping unit (12).
 7. The railway maintenance machine according to claim 4, characterised in that each tamping unit (12) has a hydraulic cylinder (18) controlled by a high-frequency servo valve (32), with three coplanar chambers, where the central chamber positions the tine-holder (19) in the configuration for single or double sleepers and transmits the vibratory force, which is adjustable in intensity and frequency, and where the two lateral chambers operate in the opposite direction to the central chamber and transmit a constant closing force to the tine-holder (19).
 8. The railway maintenance machine according to claim 4, characterised in that the vibration transmitted to the tine-holder (19) by means of the hydraulic cylinder (18), controlled by a high-frequency servo valve (32) through the vibration rod, is transferred with an oscillating movement of 25 Hz and with an amplitude of 5.6 mm when the tine enters the stones, to then be modified to a vibration of 35 Hz and 3.5 mm during the closing motion of the tines.
 9. The railway maintenance machine according to claim 2, characterised in that said two pairs of hydraulic cylinders (28A and 28B) of the slewing trolley (20) are articulated to a fixed point of the frame of said machine in such a way that in the position corresponding to the initial moment of the work cycle, with the lifting and slewing unit in its furthest forward position, the pair of hydraulic cylinders (28A) situated in the front position (28A) is contained within the plane perpendicular to the track, while at the end of the work cycle, it is the pair of hydraulic cylinders (28B) situated in the rear position that is contained in said plane, in such a way that the power loss of one system is compensated by the gain in the other due to the variation in perpendicularity with regard to the track during the movement of the lifting and slewing unit.
 10. The railway maintenance machine according to claim 5, characterised in that the aforesaid trolley (2) comprises hydraulic brake cylinders (7) articulated to the frame of the machine by a set of rods (6), where said hydraulic brake cylinders (7) are capable of exercising a downwards vertical force through the use of a brake shoe (4) on the upper surface of said trolley (2), where said force allows the trolley (2) to brake in the desired transversal position, apart from also cancelling out the vertical play in the system supported on rollers (1) during the work of the tamping unit (12).
 11. The railway maintenance machine according to claim 5, characterised in that each tamping unit (12) has a hydraulic cylinder (18) controlled by a high-frequency servo valve (32), with three coplanar chambers, where the central chamber positions the tine-holder (19) in the configuration for single or double sleepers and transmits the vibratory force, which is adjustable in intensity and frequency, and where the two lateral chambers operate in the opposite direction to the central chamber and transmit a constant closing force to the tine-holder (19).
 12. The railway maintenance machine according to claim 6, characterised in that each tamping unit (12) has a hydraulic cylinder (18) controlled by a high-frequency servo valve (32), with three coplanar chambers, where the central chamber positions the tine-holder (19) in the configuration for single or double sleepers and transmits the vibratory force, which is adjustable in intensity and frequency, and where the two lateral chambers operate in the opposite direction to the central chamber and transmit a constant closing force to the tine-holder (19).
 13. The railway maintenance machine according to claim 5, characterised in that the vibration transmitted to the tine-holder (19) by means of the hydraulic cylinder (18), controlled by a high-frequency servo valve (32) through the vibration rod, is transferred with an oscillating movement of 25 Hz and with an amplitude of 5.6 mm when the tine enters the stones, to then be modified to a vibration of 35 Hz and 3.5 mm during the closing motion of the tines.
 14. The railway maintenance machine according to claim 6, characterised in that the vibration transmitted to the tine-holder (19) by means of the hydraulic cylinder (18), controlled by a high-frequency servo valve (32) through the vibration rod, is transferred with an oscillating movement of 25 Hz and with an amplitude of 5.6 mm when the tine enters the stones, to then be modified to a vibration of 35 Hz and 3.5 mm during the closing motion of the tines.
 15. The railway maintenance machine according to claim 7, characterised in that the vibration transmitted to the tine-holder (19) by means of the hydraulic cylinder (18), controlled by a high-frequency servo valve (32) through the vibration rod, is transferred with an oscillating movement of 25 Hz and with an amplitude of 5.6 mm when the tine enters the stones, to then be modified to a vibration of 35 Hz and 3.5 mm during the closing motion of the tines. 